Granite and sink rods

SarinaOctober 5, 2013

I need some help on sink rodding info. Okay l thought the purpose of sink rodding was to give support to sink for the long haul. We are looking at two installets. One does granite by machine to cut then the rest is done by hand. He rods with stainless steel rods. The other guy which btw has the stone we like as he is a fabricator and does a lot of his own stone importing. So in talking to this guy he said only purpose of rodding is too protect for transport and if the granite ends up.with seam in middle then no rod is used. He also does not use stainless steel rods just steel as he says they can not rust as they are in epoxy.They polish by machine too except on radius is what I understood him to say. The other fabricator is saying polish by hand is best as machine polish is not as good? Help :)

I am a fabricator.
Rodding is for transport. Properly installed there is no stress on the countertop and no need for rods.

steel buried in epoxy is acceptable. If moisture is allowed to get to the steel it can rust and crack the countertop by "rust jacking", the same effect that breaks up roadways when water gets to the rebar in the concrete. some fabricators go with stainless because it eliminates this possibility but steel rods properly done are ok. (thats the way we do it.)

edges cut and shaped by machine and then finish polished by hand is definitely superior to a machine only polish.

Rodding is old school and obsolete. Fabricators have access to modern equipment which prevents breakage in transport and installation.

The Marble Institute of America recommends the use of stainless or mild steel or fiberglas bedded in epoxy but many fabricators use mild steel and polyester which is equivalent to placing a time bomb in your top. It costs about a thousand dollars to fix after it explodes.

When I started my shop 13 years ago I faced all the conflicting opinions about rodding. Since I am an engineer I decided to get actual DATA regarding rodding.

I made arrangements with the dean of material sciences at a local college to conduct a formal material strength test of rodded and unrodded sink rails. A large number of rodded and unrodded rails were tested on a hydraulic test fixture with computerized data collection. The design and conduct of the test was the senior year engineering project for 3 students so the testing and analysis was extensive.

The results were unambigious. Rodding made weak stones significantly more resistant to cracking. Surprisingly, rodding also allowed a sink rail to bend almost twice as much before cracking. I can't explain how rodding lets the stone bend more but I believe the results which were consistent across a variety of materials.

so rodded parts are measurably stronger and measurably more resistant to cracking. There are tools available to fabricators to help handle parts but they do not replace rodding.

regarding the "time bomb", polyester rods cannot create rust jacking so there is no risk with that type of rod and steel rods only represent a risk if they are improperly done. Moisture getting to rods is possible but easily avoided in a competently managed shop. we have had ZERO incidents of rust jacking in several thousand jobs.

You don't say if you tested the rodded and unrodded sink rails when installed on cabinets.

Granite successfully installed on flat and level cabinets now has all the support in tension provided by the cabinets, making the support in tension supplied by the rodding moot.

That rodding adds substantial support in tension is indisputable. Whether or not gaining that support is necessary, due to the strength in tension provided by the cabinets, or whether or not that strength is cost-effective in light of modern transportation developments is the real question.

A fabricator having to charge to install strength a customer doesn't need is at a substantial competitive disadvantage and does his customers no favors.